Backpack



FIG. 1 is a top, front, right perspective view of a backpack showing our new design;

FIG. 2 is a top front, left perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof; and,

FIG. 6 is a top view thereof.

The even-length broken lines within the shaded area represent portions of the backpack that form no part of the claim. The uneven-length broken lines immediately adjacent to the shaded area represent boundary lines that form no part of the claim. The even-length broken lines showing the remainder of the backpack are for the purpose of illustrating environment that forms no part of the claimed design. 

CLAIM The ornamental design for a backpack, as shown and described. 